feat(shader): add compute shader support and refactor pipeline

Refactored shader system to support both graphics and compute shaders.
- Updated ANTLR grammars and parser logic for explicit shader model and compute shader entry points.
- Split shader models and descriptors for graphics and compute.
- Refactored pipeline key generation and D3D12 pipeline library for compute support.
- Updated push constant layouts and HLSL includes for both shader types.
- Improved error handling and test coverage with new example files.

BREAKING CHANGE: Shader model, descriptor, and pipeline APIs have changed. Existing shader and pipeline code must be updated to use the new types and conventions.

src/Runtime/Ghost.Graphics.RHI/Common.cs

@@ -167,6 +167,7 @@ public struct ResourceRange
 
 public readonly struct ShaderVariant;
 public readonly struct GraphicsPipeline;
+public readonly struct ComputePipeline;
 
 public readonly struct ShaderPass
 {
@@ -241,6 +242,14 @@ public ref struct GraphicsPSODescriptor
     }
 }
 
+public ref struct ComputePSODescriptor
+{
+    public Key64<ShaderVariant> VariantKey
+    {
+        get; set;
+    }
+}
+
 public readonly struct CBufferPropertyInfo
 {
     public string Name